1. Field of the Invention
This invention relates to a mounting method of a bump-equipped electronic component for mounting a bump-equipped electronic component with a plurality of metallic bumps on a substrate and a mounting structure of the bump-equipped electronic component with a plurality of metallic bumps.
2. Description of the Related Art
As a technique for mounting, on a substrate, a bump-equipped electronic component such as a flip chip which is a semiconductor device equipped with metallic bumps which are electrodes for connection, ultrasonic bonding has been adopted (for example, JP-A-10-335373 and JP-A-2001-298146). In this mounting technique, by pressing the bump-equipped electronic component onto the substrate with ultrasonic oscillation, heat and applied pressure being exerted on the bump-equipped electronic component, the metallic bumps are metallic-bonded to the electrodes on the substrate through ultrasonic bonding so that the metallic bumps are electrically connected to the electrodes
Meanwhile, there are changes in the size of the metallic bumps formed on the bump-equipped electronic component. In the above ultrasonic bonding, the bumps are metallic-bonded to the electrodes in order from the bump having a larger size brought in contact with the corresponding electrode. During the bonding process, the metallic bumps are slightly crushed by pressure so that all the metallic bumps are metallic-bonded to the corresponding electrodes, thus completing the ultrasonic bonding.
However, in the above ultrasonic bonding for the bump-equipped electronic component, the degree of progress of the ultrasonic bonding is different for each metallic bump because of a difference in bump size. Therefore, the metallic bump for which the metallic bonding has been precendently started is continuously subjected to ultrasonic oscillation with the lower end having already been metallic-bonded to the electrode. The metallic bump excessively subjected to such ultrasonic oscillation suffers from an excessive stress due to oscillation displacement at the base of the bump. This leads to a problem that in the state where the ultrasonic bonding has been completed, a damage such as a crack is generated at the base of the bump.